File extensions – definition and basic information


File extensions are the integral parts of the files that are on each computer. Often, when working on a computer, we encounter a wide range of files, such as docx, ppt, part, mp3 or rmvb. We realize that they are there – but we often do not know what they are for on our computer.

File extension, also known as the filename extension is a suffix added to the name of a computer file, usually consisting of a number of characters placed after the last dot in the filename, which gives us information about its coding. In other words a file extension is a file format. It allows the operating system (e.g. Windows) to recognize what program it should try to open the file.

In the table below you will find a random selection of popular file extensions.


File extension The full name of the file Category

DRV file extension

Device Driver

System Files

AI file extension

Adobe Illustrator File

Vector Image Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

CAB file extension

Windows Cabinet File

System Files

7Z file extension

7-Zip Compressed File

Compressed Files

GZ file extension

Gnu Zipped Archive

Compressed Files

PIF file extension

Program Information File

Executable Files

CER file extension

Internet Security Certificate

Web Files

ZIP file extension

Zipped File

Compressed Files

SWF file extension

Shockwave Flash Movie

Video Files

ACCDB file extension

Access 2007 Database File

Database Files

SYS file extension

Windows System File

System Files

TARGZ file extension

Compressed Tarball File

Compressed Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

LUA file extension

Lua Source File

Developer Files